As mobile, wireless, and/or handheld portable devices increasingly become multifunctional, “all-in-one,” communication devices, these handheld portable devices integrate an increasingly wide range of functions for handling a plurality of wireless communication services. For example, a single handheld portable device may enable Bluetooth communications and wireless local area network (WLAN) communications.
Much of the front end processing for wireless communications services is performed in analog circuitry. Front end processing within a portable device may comprise a range of operations that involve the reception of radio frequency (RF) signals, typically received via an antenna that is communicatively coupled to the portable device. Receiver tasks performed on an RF signal may include low noise amplification, demodulation, filtering, and analog to digital conversion (ADC), for example. Noise considerations may be important since the strength of the received RF signal may be low. The resulting front-end processed signal may be referred to as a baseband signal. The baseband signal typically contains digital data, which may be subsequently processed in digital circuitry within the portable device.
The operation of low noise amplifiers and other components of the receiver may have to be very linear, that is, the output has to have a linear relationship with the input, to maintain the performance of the receiver. This may cause increased power consumption by the receiver due to the highly linear characteristics of various components in the receiver. Blocker signals are unwanted signals in frequency channels outside the wanted channel that disturb the reception of the wanted signals. This happens due to the fact that the blockers generate large signals within the receiver path. These large signals may introduce harmonics and intermodulation products or unwanted mixing products that crosstalk with the wanted signals. Similarly, when the required RF signal is weak, there is an increase in the power consumption of the receiver to achieve a good noise factor (NF) and a good phase noise. In handheld communication devices such as cell phones, and smart phones, the increased power consumption may significantly drain the battery that powers these devices.
For high performance receivers it is therefore important that the low noise amplifier is able to operate at low power, to perform low noise amplification, to provide reasonably high voltage gain, and to provide good input impedance matching. In this regard, novel low noise amplifier designs may need to achieve all these benefits while being able to generate output signals that may be easily utilized by subsequent processing portions of the receiver.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.